javascript dataTransfer Description

The dataTransfer object (accessible as a property of the event object) is a temporary container that scripts in IE 5 and later for Windows can use to transfer text data, particularly during script-controlled operations that simulate cutting, copying, and pasting, or that control dragging. Your script controls what data is stored in the dataTransfer object, such as just the text of an element, an element's entire HTML, or the URL of an image. For example, a page for children could display simple icon images of several different kinds of animals. If the user starts dragging the dog icon, the script initiated by the img element's ondragstart event handler can store a custom attribute value of that element (perhaps the URL of a pretty dog photo) into the dataTransfer object. When the user drops the icon into the designated area, the ondrop event handler's function reads the dataTransfer object's data, and loads the photo image into position on the page.